The Collaborative International Dictionary of English v.0.48:

Ochlocracy \Och*loc"ra*cy\, n. [Gr. ?; 'o`chlos the populace,
   multitude + kratei^n to be strong, to rule, kra`tos strength:
   cf. F. ochlocratie.]
   A form of government by the multitude; a mobocracy; mob
   rule. --Hare.
   [1913 Webster] Ochlocratic

Moby Thesaurus II by Grady Ward, 1.0:

79 Moby Thesaurus words for "mob rule":
   absolute monarchy, anarchism, anarcho-syndicalism, anarchy,
   antinomianism, aristocracy, autarchy, autocracy, autonomy, chaos,
   coalition government, colonialism, commonwealth, confusion,
   constitutional government, constitutional monarchy,
   criminal syndicalism, democracy, dictatorship, disorder,
   disorderliness, disorganization, disruption, dominion rule,
   duarchy, duumvirate, dyarchy, federal government, federation,
   feudal system, garrison state, gerontocracy, heteronomy, hierarchy,
   hierocracy, home rule, limited monarchy, lynch law, martial law,
   meritocracy, militarism, military government, misrule, mob law,
   mobocracy, monarchy, neocolonialism, nihilism, ochlocracy,
   oligarchy, pantisocracy, patriarchate, patriarchy, police state,
   primal chaos, pure democracy, rebellion, regency,
   representative democracy, representative government, republic,
   revolution, self-determination, self-government, social democracy,
   stratocracy, syndicalism, technocracy, thearchy, theocracy,
   tohubohu, totalitarian government, totalitarian regime, triarchy,
   triumvirate, turmoil, tyranny, unruliness, welfare state